The Google Compute Engine (GCE) Cloud plugin allows to use GCE API for the unicast discovery mechanism.
'org.elasticsearch:elasticsearch-cloud-gce:2.3.0'
<dependency>
<groupId>org.elasticsearch</groupId>
<artifactId>elasticsearch-cloud-gce</artifactId>
<version>2.3.0</version>
</dependency>
<dependency org="org.elasticsearch" name="elasticsearch-cloud-gce" rev="2.3.0"/>
"org.elasticsearch", "elasticsearch-cloud-gce", "2.3.0"